High temperature processing of photographic elements

ABSTRACT

1. METHOD OF PRODUCING PHOTOGRAPHIC IMAGES BY DEVELOPMENT IN A PROCESS WHICH EMPLOYS ROLLERS AT A TEMPERATURE AVOVE 30*C. OF AN EXPOSED PHOTOGRAPHIC SILVER HALIDE MATERIAL COMPRISNG AT LEAST ONE SILVER HALIDE EMULSION LAYER WHEREIN THE SAID EMULSION LAYER OR A HYDROPHILIC COLLOID LAYER IN WATER-PERMEABLE RELATIONSHIP THEREWITH COMPRISES A POLYMERIC COMPOUND, WHICH IS A POLYMER WHEREIN AT LEAST 15 MOLE PERCENT OF THE RECURRING UNITS ARE OF A N-HYDROXYALKYL(METH)ACRYLAMIDE OR OF A LOWER ALKYL ETHER THEREOF, WHEREIN THE ALKYL GROUPS REFERRED TO ARE C1-C5 ALKYL GROUPS, WHEREBY THE PRESSURE MARKS ON SAID MATERIAL ARE REDUCED.

United States Patent C US. C]. 9650 R 8 Claims ABSTRACT OF THE DISCLOSURE A method is provided of producing photographic images by development at a temperature above 30 C. of an exposed photographic silver halidematerial comprising at least one silver halide emulsion layer wherein the said emulsion layer or a hydrophilic colloid layer in water-permeable relationship therewith comprises a polymeric compound, which is a homopolymer or copolymer of a N-hydroxyalkyl(meth) acrylamide or of a lower alkyl ether thereof, wherein the alkyl groups referred to are C -C alkyl groups. The polymeric compound reduces the formation of pressure marks by processing at elevated temperature and the emulsion speed and gradation are not affected to a noteworthy extent.

The present invention relates to rapid processing at elevated temperature of exposed photographic radiationsensitive silver halide elements.

It is known to use techniques for automatic processing of exposed photographic materials. In order to reduce the time the materials need for passing through the automatic processing machines, where they are conducted from one processing station to another by means of roller pairs, processing is carried. out at elevated temperatures, say above 30 C. Under these severe processing conditions the physical and photographic properties of the materials are impaired the more because in these materials for rapid processing the gelatin content of the silver halide emulsions is reduced considerably as compared with the gelatin content used in emulsions for normal processing. For instance, owing to the very low gelatin content, the machine-processed materials show repeated pressure marks from the roller pairs by which they are guided in the processing machine.

It is possible to eliminate these pressure marks by appropriate hardening of the material, more particularly of the protective gelatin top layer but with these short processing times this unfortunately results in a unacceptable lowering of the gradation and also of the emulsion speed.

It has now been found possible to reduce or eliminate the pressure marks described above without elfecting the gradation and emulsion speed to a noteworthy extent by incorporating in the radiation-sensitive silver halide emulsion with low gelatin content or a hydrophilic colloid layer in water-permeable relationship with the said emulsion layer a polymer or copolymer of a N-hydroxyal'kyl- (meth)acrylamide or lower alkyl ether thereof wherein the alkyl groups referred to are C C alkyl groups.

The silver halide emulsions for being processed after exposure at elevated temperature in an automatic processing machine are silver halide emulsions having a very low content of hydrophilic colloid e.g. gelatin. The ratio of hydrophilic colloid, more particularly gelatin, to silver halide expressed as silver nitrate is generally comprised between 0.2 and 0.6.

The present invention thus provides a method of producing photographic images by exposure and processing at a temperature above C. of a photographic silver halide material comprising at least one silver halide emulsion layer wherein the said emulsion layer or a hydrophilic colloid layer in water-permeable relationship therewith comprises a polymeric compound as defined above.

The polymeric compounds for use according to the present invention are homopolymers or copolymers. The polymeric materials may comprise in addition to the recurring units of N-hydroxyalkyl lmeth)acrylamides or ethers thereof, recurring units of other copolymerized monomers for example recurring units of acrylic acid and methacrylic acid, acrylamide and methacrylamide as well as the N-alkylated derivatives thereof, alkyl acrylates and alkyl methacrylates, acrylonitrile, ethylene, vinyl acetate, vinyl ethers especially those whose aliphatic ether group comprises at most 4 C-atoms, styrene, butadiene, etc. i

The effectiveness of the polymeric compounds for use according to the present invention :is due to the recurring units of an N-hydroxyalkyl(meth)acrylam,ide or of an ether thereof, and therefore homopolymers are preferred. If copolymers are employed they comprise at least 15 mole percent, preefrably at least 50 mole percent, of these recurring units. The copolymerized monomers should be such that they have no deleterious effect on the photographic properties of the silver halide emulsion layers.

Though the molecular Weight of the polymeric compounds used is of minor importance and the best range can be easily determined by means of some simple tests, the compounds generally have a molecular weight comprised between 10 and 10 The following are representative examples of polymeric compounds for use in accordance with the present invention. They can be prepared according to known methods and as illustrated hereinafter.

(a) poly(N-methoxymethylmethacrylamide) prepared as described in Belgian Patent Specification 666,067 filed June 29, 1965, by Agfa-Gevaert NV. and copolymers thereof with acrylamide or methacrylamide as described in the same Belgian Patent Specification.

(b) poly(N-hydroxymethylacrylamide): 0.6 mole of polyacrylamide was dissolved at room temperature in 350 ml. of demineralized water. Sodium hydroxide (1 N) was added to bring the pH to 8.4 whereupon the solution was heated to C. With stirring and While keeping the solution at 35 C., 36 ml. of 40% aqueous formaldehyde and 100 ml. of water added. The pH of the solution had diminished to pH 5 and by addition of 1 N sodium hydroxide it was brought to pH 10. The mixture was stirred for 2 /2 hours at 35 C. whereupon it was neutralized to pH 7 by addition of 1 N hydrochloric acid. The solution was diluted to a volume of 1140 ml. By nitrogen analysis of the lyophilized poly meric material it was found that the polyacrylamide was almost completely converted into poly(N-hydroxymethylacrylamide) (theor.: 13.85; found: 13.55- 13.80).

(c) co(N-hydroxyethylmethacrylamide/butyl acrylate) latex: In a 500 ml. reaction vessel were placed 275 ml. of demineralized water and 3 g. of oleyl methyl tauride sodium salt, The solution was rinsed with liquid nitrogen and heated to C. Rinsing with nitrogen was stopped and the following solutions were then added one after the other by means of a. dropping funnel:

(a) 1 quarter of the solution formed by mixing 30 g.

of N-hydroxyethylmethacrylamide to 30 g. of butyl acrylate (b) 1 quarter of a solution formed by diluting with water 6 ml. of a 5% aqueous solution of 4,4'-azobis(4-cyanovaleric acid) to make 25 ml.

3 When polymerization had started the remainders of the above solutions were added simultaneously in 30 minutes. After 2 hours of after-polymerization at 95 C. a slightly viscous latex was obtained comprising no pre cipitate, having pH 7 and a content of 17% of solids. (d) co(ethyl acrylate-hydroxymethyldiacetonacrylamide) latex: In a 2 litre reaction vessel fitted with three dropping funnels A, B and C Were placed: 800 ml. dcmineralized Water and 16 g. of oleylmethyl tauride sodium salt. The solution was rinsed with liquid nitrogen and heated to 80 C. Rinsing with nitrogen was then stopped. In dropping funnel A were placed 180 g. of ethyl acrylate, in dropping funnel B 20 g. of a 55% aqueous solution of hydroxymethyldiacetonacrylamide of the formula CH3 R 0 R CHz=CIICONHi3-J3y) R In R 1 1 wherein R is hydrogen or hydroxymethyl, at least one of the Rs being hydroxymethyl and the total hydroxyl content being 6.5% (Lubrizol HMDAA marketed by the Lubrizol Corporation, Cleveland, Ohio, U.S.A.), and in dropping funnel C 600 mg. of potassium peroxodisulphate dissolved in 40 ml. of water. From each of the droppings funnels 1 quarter of the volumes was added to the aqueous solution heated to 80 C. When polymerization had started the 3 other quarters were added simultaneously at such speed that the mixture refluxed regularly. When all of the solutions was added another 60 mg. of potassium peroxodisulphate dissolved in 10 ml. of water were added. The mixture was afterpolymerized for 45 minutes at 95 C. Yield: 910 ml. of latex free of precipitate and containing 22.8% of solids.

The polymeric compounds for use according to the present invention may be present in the silver halide emulsion or another layer of the photographic material e.g. a gelatin antistress layer or intermediate layer, which is in water-permeable relationship with the said emulsion layer. When used in the silver halide emulsion, they may be added during no matter what step of emulsion preparation, preferably just before coating on a suitable support e.g. paper, glass or film such as cellulose triacetate and polyethylene terephthalate.

The polymeric compounds of the use according to the present invention may be used in any type of light-sensitive material that after exposure is intended to be mechanically processed at elevated temperature. Various silver salts may be used as light-sensitive salt, e.g. silver bromide, silver iodide, silver chloride, or mixed silver halides, e.g. silver chlorobromide or silver bromoiodide. The invention is of particular importance for mechanical processing at elevated temperature of silver bromoiodide emulsions. The emulsion may be a negative emulsion or a direct-positive emulsion, which comprises fogged silver halide. In directpositive emulsions fogging may be etfected by known means, e.g. by light and preferably, by chemical sensitization to fog e.g. by means of reducing agents such as hydroxylamine, hydrazine, formaldehyde, tin(II)chloride, thiourea dioxide, etc., and/or by means of noble metal compounds such as gold compounds. In addition thereto fogging may also occur by increasing the pH of the emulsion by means of alkaline substances such as sodium or potassium hydroxide.

The silver halides are dispersed in the common hydrophilic colloids such as gelatin, casein, zein, polyvinyl alcohol, carboxymethylcellulose, alginic acid, etc., gelatin, however, being favoured.

The amount of polymeric compound employed in the light-sensitive silver halide emulsion layer or the col loid layer in water-permeable relationship therewith depends on the particular compound, the particular type of emulsion and the desired effect and can vary within very wide limits. The optimum amount of each individual polymeric compound to be added is best determined for each particular type of emulsion by trial. Generally, the most suitable concentration in the particular colloid layer involved is comprised between 5 and 50% by weight relative to the weight of the hydrophilic colloid. The polymeric compounds may be added in the form of loose powder but preferably they are added from an aqueous solution or dispersion (i.e. a latex).

The silver halide emulsions of the radiation-sensitive elements comprising the polymeric compounds in accordance with the present invention may be chemically as well as spectrally sensitized. They may be chemically sensitized by any of the accepted procedures. The emulsions may be digested with naturally active gelatin or sulphur compounds may be added such as allyl thiocyanate, allyl thiourea, sodium thiosulphate, etc. The emulsions may also be sensitized by means of reductors, e.g. tin compounds as described in our United Kingdom Patent Specification 789,823 filed Apr. 29, 1955 by Gevaert Photo-Producten N.V. and by means of small amounts of noble metal compounds, e.g. of gold, platinum, palladium, iridium, ruthenium and rhodium as described by R. K0- slowsky Z. Wiss. Phot. 46, 67-72 (1951). Representative noble metal compounds are ammonium chloropalladate, potassium chloroplatinate, potassium chloroaurate and potassium aurithiocyanate. These chemical sensitizers may be added separately or together during no matter what step of emulsion preparation e.g. before, during or after the chemical ripening.

The emulsions may further comprise compounds that sensitize the emulsion by development acceleration for example alkylene oxide polymers. These alkylene oxide polymers may be of various type e.g. polyethylene glycol having a molecular weight of 1500 or more, alkylene oxide condensation products or polymers as described among others in United States Patent Specifications 1,970,578 of Conrad Schoeller and Max. Wittner issued Aug. 21, 1934, 2,240,472 of Donald R. Swan issued Apr. 29, 1941, 2,423,- 549 of Ralph Kinsley Blake, William Alexander Stanton and Ferdinand Schulze issued July 8, 1947, 2,441,389 of Ralph Kinsley Blake issued May 11, 1948, 2,531,832 of William Alexander Stanton issued Nov. 28, 1950, and 2,533,990 of Ralph Kinsley Blake issued Dec. 12, 1950, in United Kingdom Patent Specifications 920,637 filed May 7, 1959, 940,051 filed Nov. 1, 1961, 945,340 filed Oct. 23, 1961 all by Gevaert Photo-Producten N.V. and 991,608 filed June 14, 1961 by Kodak Co. and in Belgian Patent Specification 648,710 filed June 2, 1964 by Gevaert Photo-Proucten N.V. Other compounds that sensitize the emulsion by development acceleration and that are suitable for use in combination with the polymeric compounds of use according to the invention are the quaternary ammonium and phosphonium compounds and ternary sulphonium compounds as Well as onium derivatives of amino-N-oxides as described in United Kingdom Patent Specification 1,121,696 filed Oct. 7, 1965 by Gevaert- Agfa N.V.

The emulsions may be spectrally sensitized e.g. by means of the common methine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, oxonol dyes and the like. Suchlike spectrally sensitizing dyes have been described by F. M. Hamer in The Cyanine Dyes and Related Compounds (1964). Direct-positive emulsions may comprise desensitizing dyes e.g. as described in United Kingdom Patent Specification 1,155,404 filed May 9, 1966 by Gevaert-Agfa N.V.

The emulsions may comprise the common emulsion stabilizers e.g. homopolar or salt-like compounds of mercury with aromatic and heterocyclic rings (e.g. mercaptotriazoles) simple mercury compounds, mercury sulphonium double salts and other mercury compounds of the king described in Belgian Patent Specifications 524,121 filed Nov. 7, 1953 by Kodak Co., 677,337 filed Mar. 4, 1966, 707,386 filed Dec. 1, 1967 and 709,195 filed Jan.

11, 1968 all by Gevaert-Agfa N.V. Other suitable emulsion stabilizers are the azaindenes, particularly the tetraor pentaazaindenes and especially those substituted by hydroxyor amino groups. Suchlike compounds have been described by Birr in Z. wiss. Phot. 47, 2-58 (1952). The emulsions may further comprise as stabilizers heterocyclic nitrogen-containing mercapto compounds such as benzothiazoline 2-thione and l-phenyI-S-mercapto-tetrazole, sulphinic acids such as benzenesulphinic acid and toluenesulphinic acid, thiosulphonic acids such as benzenethiosulphonic acid, toluenethiosulphonic acid, p-chlorobenzenethiosulphom'c acid sodium salt, propylthiosulphonic acid potassium salt, butylthiosulphonic acid potassium salt, etc. They may further comprise or by developed in the presence of compounds that are particularly effective as antifoggants for materials that are processed at elevated temperatures e.g. heterocyclic compounds with nitro-substituents e.g. nitroindazole and nitrobenzo-triazole as described in French Patent Specification 2,008,245 filed May 9, 1969 by Eastman Kodak Co., nitrobenzylidene pyridinium and nitrobenzylidene quinolinium compounds as well as the onium compounds described in published German Patent Application 2040876 filed Aug. 18, 1970 by Kunishiroku Photo Industry Co. Ltd.; further the nitrobenzene compounds described in co-pending Application 43,517/71 filed Sept. 17, 1971 by Agfa-Gevaert N.V. and the nitrile compounds described in co-pending Application 43,518/71 filed Sept. 17, 1971 by Agfa-Gevaert N.V.

The photographic silver halide materials may further comprise surface-active compounds, e.g. the fiuorinated surfactants of Belgian Patent Specification 742,680 filed Dec. 5, 1969 by Gevaert-Agfa N.V., plasticizers, matting agents, e.g. polymethyl methacrylate and silica particles, colour couplers, hardening agents e.g. formaldehyde, dialdehydes, halogen-substituted aldehyde acids such as mucochloric and mucobromic acid, etc.

In order to promote the compatibility of the polymeric compounds used according to the invention with the hydrophilic colloid, especially gelatin, it may be advantageous to add as is described in French Patent Specification 1,535,338 filed Aug. 31, 1967 by Fuji Shashin Film K.K., a water-soluble high molecular weight aromatic sulphonic acid, e.g. homopolymers and copolymers of styrenesulphonic acid, or to add special surface-active compounds e.g. sodium oleyl methyl tauride.

As is known in the automatic processing at elevated temperatures of radiation-sensitive silver halide elements it is preferred to use a hardening developer. In these developers the hardening agent is generally an aldehyde hardener particularly aliphatic dialdehydes e.g. maleic aldehyde and glutaraldehyde which may be used as such or in the form of their bisulphite addition products.

The following examples illustrate the present invention.

EXAMPLE 1 A direct positive silver iodobromide emulsion containing 95 g. of silver halide (98 mole percent of silver bromide and 2 mole percent of silver iodide) was prepared. The ratio of hydrophilic colloid to silver halide expressed as silver nitrate was 0.45.

After addition of a desensitising nitro-styryl or nitrobenzylidene dye and a methine dye, as described in United Kingdom Patent Specification 1,155,404 as cited above and the necessary wetting agents and hardening agents (mucochloric acid), the emulsion was divided into two aliquot portions A and B. To portion B g. of poly- (N-methoxymethylmethacrylamide) prepared as described in Belgian Patent Specification 666,067 as cited above were added per kg. of emulsion. The two emulsions were coated under identical circumstances on a polyethylene terephthalate support and then overcoated with a gelatin antistress layer'comprising as coating aids etho-xylated nonylphenol having from 9 to 10 recurring ethylene oxide units and sodium isotetradecyl sulphate. To the coating solution of the gelatin protective layer for emulsion B a supplementary amount of 640 mg. of formaldehyde per litre was added in order to re-establish the hardening partly lost by the addition of the polymeric compound to the emulsion.

The two materials were exposed through a continuous grey wedge with constant 0.15 by means of incandescent bulbs.

The exposed materials were processed in an automatic seconds processing machine. Development occurred for 23 seconds at 35 C. in Agfa-Gevaerts hardening developer for automatic processing G 138, which comprises hydroquinone and l-phenyl 3 pyrazolidinone as developing agents and glutaraldehyde as hardener.

The sensitometric results are listed in the following table.

The values given for the total speed are relative values with respect to reference material A, the total speed of which has been given a value of 100. The total speed is denoted in the table by the letter S. The density in the exposed areas in a measure of the brightness of the whites and is denoted in the table by D The maximum density and gradation are denoted by D and g.

The table also includes values for the abrasion resistance (A.R.). These values are the pressures (in gram) necessary to be applied to a steel ball having a diameter of A" to make it penetrate completely through the wet photographic element on which the ball is placed, when the ball is drawn over the material.

TABLE Material min a S Dmx A.R.

A 0. 03 l. 50 3. 20 290 B 0.03 1. 41 2. 90 230 EXAMPLE 2 A silver bromoiodide X-ray emulsion (2 mole percent iodide) comprising per kg. an amount of silver halide equivalent to g. of silver nitrate, 74 g. of gelatin, 545 mg. of S-methyl 7 hydroxy-s-triazole[1,5-a]pyrimidine, 6.5 mg. of 1 phenyl 5 mercaptotetrazole and 0.45 mg. of mercury cyanide was divided into three aliquot portions A, B and C.

To emulsion portion B 20 g. of poly(N-methoxymethylmethacrylamide) prepared as described in Belgian Patent Specification 666,067 as cited above were added per kg. and to emulsion portion C 10 g. of this polymeric compound were added per kg.

The three emulsion portions were coated under identical circumstances on a polyethylene terephthalate support and then overcoated with a gelatin antistress layer comprising formaldehyde as hardening agent. To the coating solutions of the gelatin protective layers for emulsions B and C a supplementary amount of 50 and 25 percent of formaldehyde was added respectively in order to reestablish the hardening partly lost by the addition of the polymeric compound to the emulsion.

The materials were exposed through a continuous wedge with constant 0.15 and then automatically processed in a 90 seconds processing machine. Development occurred for 23 seconds at 35 C. in Agfa-Gevaerts hardening developer for automatic processing G 138, which comprises hydroquinone and 1-phenyl3-pyrazolidinone as developing agents and glutaraldehylde as hardener.

The sensitometric results obtained are listed in the table below.

Material Fog Gradation Speed A. R

A 0. 04 2. 82 100 110 B 0. 03 2. 52 87 100 C O. 04 2. 6O 01 J Whereas the automatically processed material A was of unsatisfactory quality because of the pressure marks material B showed no pressure marks at all and material C showed practically no pressure marks.

We claim:

1. Method of producing photographic images by development in a process which employs rollers at a temperature above 30 C. of an exposed photographic silver halide material comprising at least one silver halide emulsion layer wherein the said emulsion layer or a hydrophilic colloid layer in water-permeable relationship therewith comprises a polymeric compound, which is a polymer wherein at least 15 mole percent of the recurring units are of a N-hydroxyalkyl(meth)acrylamide or of a lower alkyl ether thereof, wherein the alkyl groups referred to are C -C alkyl groups, whereby the pressure marks on said material are reduced.

2. Method according to claim 1, wherein the polymeric compound is a homopolymer of a N-hydroxyalkyl(meth) acrylamide or of a lower alkyl ether thereof, wherein the alkyl groups referred to are C C alkyl groups.

3. Method according to claim 2, wherein the said polymeric compound is poly(N methoxymethylmethacrylamide) 4. Method according to claim 1, wherein the said polymeric compound is present in the said layer in an amount of 5 to by weight relative to the weight of dry hydrophilic colloid.

5. Method according to claim 1, wherein in the said emulsion layer the ratio of hydrophilic colloid to silver halide is comprised between 0.2 and 0.6.

6. Method according to claim 1, wherein the emulsion is a silver bromoiodide emulsion.

7. Method according to claim 1, wherein development occurs by means of a hardening developer.

8. Method according to claim 7, wherein the developer comprises glutaraldehyde.

References Cited UNITED STATES PATENTS 3,335,004 8/1967 Wrisley et al 9666 R 3,408,199 10/1968 Saleck 96114 3,516,830 6/1970 Whiteley 9667 3,533,793 10/1970 Whiteley 9667 3,591,379 7/1971 Plakunov 9650 3,600,174 8/1971 Milton 9666 3,625,689 12/1971 Salesin 9666 3,713,829 1/1973 Nishio 961 14 MARY F. KELLEY, Primary Examiner US. Cl. X.R. 9666 R, R, 114 

1. METHOD OF PRODUCING PHOTOGRAPHIC IMAGES BY DEVELOPMENT IN A PROCESS WHICH EMPLOYS ROLLERS AT A TEMPERATURE AVOVE 30*C. OF AN EXPOSED PHOTOGRAPHIC SILVER HALIDE MATERIAL COMPRISNG AT LEAST ONE SILVER HALIDE EMULSION LAYER WHEREIN THE SAID EMULSION LAYER OR A HYDROPHILIC COLLOID LAYER IN WATER-PERMEABLE RELATIONSHIP THEREWITH COMPRISES A POLYMERIC COMPOUND, WHICH IS A POLYMER WHEREIN AT LEAST 15 MOLE PERCENT OF THE RECURRING UNITS ARE OF A N-HYDROXYALKYL(METH)ACRYLAMIDE OR OF A LOWER ALKYL ETHER THEREOF, WHEREIN THE ALKYL GROUPS REFERRED TO ARE C1-C5 ALKYL GROUPS, WHEREBY THE PRESSURE MARKS ON SAID MATERIAL ARE REDUCED. 